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"""Import basic exposure of libzmq C API as a backend"""
# Copyright (C) PyZMQ Developers
# Distributed under the terms of the Modified BSD License.
import os
import platform
import sys
from zmq.utils.sixcerpt import reraise
from .select import public_api, select_backend
if 'PYZMQ_BACKEND' in os.environ:
backend = os.environ['PYZMQ_BACKEND']
if backend in ('cython', 'cffi'):
backend = 'zmq.backend.%s' % backend
_ns = select_backend(backend)
else:
# default to cython, fallback to cffi
# (reverse on PyPy)
if platform.python_implementation() == 'PyPy':
first, second = ('zmq.backend.cffi', 'zmq.backend.cython')
else:
first, second = ('zmq.backend.cython', 'zmq.backend.cffi')
try:
_ns = select_backend(first)
except Exception:
exc_info = sys.exc_info()
exc = exc_info[1]
try:
_ns = select_backend(second)
except ImportError:
# prevent 'During handling of the above exception...' on py3
# can't use `raise ... from` on Python 2
if hasattr(exc, '__cause__'):
exc.__cause__ = None
# raise the *first* error, not the fallback
reraise(*exc_info)
globals().update(_ns)
__all__ = public_api
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